Water Pump Impeller Kit – Fits Mercury/Mariner 30–70 HP 2-Stroke Outboards (Replaces 77177A3, 46-77177A3)
Water Pump Impeller Kit – Fits Mercury/Mariner 30–70 HP 2-Stroke Outboards (Replaces 77177A3, 46-77177A3) is backordered and will ship as soon as it is back in stock.
Worry-free returns
Worry-free returns
Shop with confidence. If you’re not completely satisfied, eligible items may be returned within the return window, provided they are unused and in original packaging.
If the return is due to our error or a defective item, we’ll make it right.
Please contact us before returning any item.
Delivery and Shipping
Delivery and Shipping
Orders are typically processed within 1–2 business days.
U.S. orders usually arrive within 6–15 days, depending on stock location and destination.
International delivery times may vary due to customs processing.
Tracking information will be provided once your order ships.
Water Pump Impeller Kit – Fits Mercury/Mariner 30–70 HP 2-Stroke Ou...
Water Pump Impeller Kit – Fits Mercury/Mariner 30–70 HP 2-Stroke Outboards (Replaces 77177A3, 46-77177A3) is backordered and will ship as soon as it is back in stock.
Product Details
This water pump impeller kit is intended for servicing the lower unit of selected Mercury and Mariner 2-stroke outboard motors in the 30–70 HP range. It is designed to help restore water-pump performance and support proper engine cooling on the applications listed below. Always verify the exact model, year, and serial number before ordering.
The kit is listed as a replacement for Mercury references 46-77177A3 and 77177A3, with additional aftermarket references including Sierra 18-3324, Mallory 9-48312, and GLM 12100. Reference numbers should be compared with the original component and engine application before installation.
- Installation location: Water pump assembly in the lower unit/gearcase.
- Housing material: Nylon PA66 plastic.
- Product type: Water pump impeller service kit with housing, base, face plate, gaskets, seals, and related hardware as listed below.
- Application: Selected Mercury and Mariner 30–70 HP 2-stroke outboards; serial-number verification is required.
Part Number Matrix
Use these references as comparison numbers only. Confirm the engine application and original part configuration before purchase.
| Brand | Part Number |
|---|---|
| Mercury | 46-77177A3 |
| Mercury | 77177A3 |
| Sierra | 18-3324 |
| Mallory | 9-48312 |
| GLM | 12100 |
Engine & Model Compatibility
The following applications are listed for this kit. Model, horsepower, stroke, year, and serial-number conditions must be considered together. Do not rely on horsepower or model name alone.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Serial Conditions |
|---|---|---|---|---|---|---|
| Mercury | 30 JET | 30 | 2-Stroke | 1989–1997 | 46-77177A3 | 0C159200–0G589999 |
| Mercury | 35 | 35 | 2-Stroke | 1984–1989 | 46-77177A3 | 6445653 and up |
| Mercury | 402 | 40 | 2-Stroke | 1978–1979 | 46-77177A3 | 4860103–5556229 |
| Mercury | 40 (2 CYL) | 40 | 2-Stroke | 1980–1983 | 46-77177A3 | 5556230–6445653 |
| Mercury | 40 (4 CYL) | 40 | 2-Stroke | 1989–1997 | 46-77177A3 | 0C159200 and up |
| Mercury | 45 (4 CYL) | 45 | 2-Stroke | 1986–1997 | 46-77177A3 | 5531630 and up |
| Mercury | 50 (4 CYL) | 50 | 2-Stroke | 1978–1985 | 46-77177A3 | 496205–6 and up |
| Mercury | 50 (3 CYL) | 50 | 2-Stroke | 1984–1990 | 46-77177A3 | 6428681–0D000749 |
| Mercury | 60 (3 CYL) | 60 | 2-Stroke | 1984–1990 | 46-77177A3 | 6428681–0D000749 |
| Mercury | 65 (650) (3 CYL) | 65 | 2-Stroke | 1976 | 46-77177A3 | 4382057–4571651 |
| Mercury | 70 (3 CYL) | 70 | 2-Stroke | 1979–1983 | 46-77177A3 | 4977157–6428680 |
Technical Specs
- Product Type
- Water pump impeller kit with housing
- Installation
- Lower unit/gearcase water pump replacement
- Housing Material
- Nylon PA66 plastic
- Housing Color
- Black
- Dimensions
- 152.4 mm × 102.9 mm × 52.1 mm (6 × 4.06 × 2.05 in)
- Weight
- 0.22 kg (0.5 lb)
- Replacement Type
- Aftermarket replacement kit; not an OEM-branded assembly
What’s in the Box
- 1 × Water Pump Impeller (47-89983T)
- 1 × Upper Pump Housing (77822A1)
- 1 × Water Pump Base (46-77177A1)
- 1 × Face Plate (32768/54705)
- 1 × Impeller Key (8M0032837)
- 1 × Drain Gasket (12-20260)
- 1 × Lower Water Pump Base to Face Plate Gasket (27-19553)
- 1 × Upper Face Plate to Body Gasket (27-32770/27-19551)
- 1 × Water Pump Base Gasket (27-32771)
- 1 × Water Pump Base Gasket (27-77417/27-19552)
- 1 × Drain Plug (12-49221-1)
- 1 × O-Ring (25-26722)
- 1 × Rubber Washer (25-20273)
- Various seals and additional O-rings
Installation Notes
- Disconnect the engine battery and place the outboard in neutral.
- Remove the lower-unit mounting bolts and carefully lower the gearcase.
- Remove the existing water-pump housing assembly from the lower unit.
- Remove the old impeller, face plate, gaskets, and impeller key.
- Clean all mating surfaces and remove old gasket material and corrosion.
- Install the applicable new gasket, face plate, and impeller key.
- Install the new impeller on the driveshaft, turning the shaft clockwise as needed to position the vanes.
- Install the housing and new gaskets according to the engine service procedure.
- Tighten the housing fasteners to the manufacturer’s specified torque.
- Reinstall the lower unit, aligning the driveshaft, shift shaft, and water tube.
- Tighten the lower-unit fasteners, reconnect the battery, and test for a steady telltale stream before normal operation.
Troubleshooting & FAQ
How do I know if this kit fits my motor?
Compare your engine brand, model, horsepower, stroke, year, and serial number with the compatibility table. Serial-number verification is especially important because water-pump configurations can change within the same model family.
What are the signs of a failing water-pump impeller?
Possible signs include a weak or missing telltale stream, an overheating warning, steam from the exhaust, or reduced cooling performance. Stop operating the engine if it overheats and investigate the cooling system.
How often should the impeller be replaced?
Inspect the impeller during scheduled maintenance and replace it when the vanes show wear, cracking, deformation, or loss of flexibility. Service intervals can vary with operating hours, saltwater exposure, sand, and debris.
Is the housing included?
Yes. This listing is for a kit that includes the upper pump housing, water-pump base, impeller, face plate, impeller key, gaskets, seals, and related items listed in the package contents.
My serial number is not listed. Will it fit?
Do not assume fitment from the model or horsepower alone. Compare the original water-pump assembly and part references, and confirm the serial range with a qualified marine technician or the applicable service information before ordering.
Is this an OEM part?
No. This is an aftermarket replacement kit intended to correspond to the listed applications and reference numbers. It is not sold as an original Mercury or Mariner branded assembly.
How fast is shipping and what does it cost?
Shipping availability, delivery time, and cost depend on destination and the options shown at checkout.
What is the return policy?
Returns and replacements are subject to the applicable store policy. Contact customer support before returning a part, particularly if it has been installed or exposed to fuel, oil, water, or sealants.
Safety & Important Information
- Verify the part references, dimensions, package contents, and serial-number range against your original assembly before purchase.
- This is an aftermarket replacement part, not an original equipment manufacturer component.
- Follow the engine manufacturer’s service procedure and torque specifications.
- Professional installation is recommended if you are not experienced with outboard lower-unit service.
About Sea Sierra
- Marine Replacement Parts — Parts are offered for common service and repair applications across a range of marine engines.
- Application-Focused Support — Use the model, year, horsepower, stroke, and serial information to help confirm the correct replacement.
- Direct Product Value — Replacement components are supplied as practical alternatives for maintenance and repair.
Payment & Security
Payment methods
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
